Re: The 5-minute interval in sys.smon_scn_time table

"Anurag Varma" <avoracle_at_gmail.com> wrote in message news:1165004234.088500.36080_at_80g2000cwy.googlegroups.com...

> In 10.2 smon_scn_time table has changed quite drastically. Oracle seems
> to be trying to do a better job at mapping scn with time in 10.2.
>
> Re: Op's question, in our databases I do not see the 5 min interval
> followed in any of the databases that rigorously (checked in 9.2.0.8
> and 10.2).
> I guess smon tries to update the table approx every 5 mins .. but might
> skip updates.
> So the correct wording should probably be that in best case scenario,
> the table will be updated every 5 mins.
>
> Approx 5 days data seems to be kept in this table. In 9i this table had
> 1440 rows however in 10.2 the 1440 number does not seem to be followed.
> Instead oracle seems to be following a max mapping number of 144000
> (select sum(num_mappings) + count(*) from smon_scn_time;)
>
>
> Anurag
>

Anurag,

I think what you're seeing there is a different timeout being used to gather scn/time pairs. It's the 3-second timeout that so many processes for idling.

Something, somewhere, is building a string of scn/times at three seconds intervals, which smon picks up and dumps to the smon_scn_time table every 5 minutes in comlum tim_scn_map.

-- 
Regards

Jonathan Lewis
http://jonathanlewis.wordpress.com

Author: Cost Based Oracle: Fundamentals
http://www.jlcomp.demon.co.uk/cbo_book/ind_book.html

The Co-operative Oracle Users' FAQ
http://www.jlcomp.demon.co.uk/faq/ind_faq.html